Electric circuit breaker of the gas-blast type



Dec. 12, 1944. D. F. AMER ETAL' 2,365,132

ELEC'IRIC CIRCUIT BREAKER OF THE GAS-BLAST TYPE Filed Sept. 29, 1942 2Sheets-Sheet 1 D. AMER Ei-AL 2,365,132

ELECTRIC CIRCUIT BREAKER OF THE GAS-BLAST TYPE Filed Siit; 29 1942 2Sheets-Sheet 2- I el/b'itsc,

Attorney S Patented Dec. 1 2, 1944 ELECTRIC CIRCUIT BREAKER OF THEGAS-BLAST TYPE Donald Foster Amer, Newcastle-on-Tync, and ArthurRawling. Wallscnd-on-Tyne, England, assignors to A. Reyrolle & CompanyLimited, Hebburn-on-Tyne, England, a company of Great BritainApplication September 29, 1942, Serial No. 460,160 In Great BritainSepteniher 25, 1941 (El. Edd- 1423) 16 Claims.

circuit-breake13 the-fir" such that any restrikihg of t' s ce and willbe readily provision in a posi arc, with co ula ior n the dischargepassage necessarily exposed to the uent risk of an insulation breal:down or of ha fol effect on the performance of the circuit owing to thegeneration by the action of the are on the insulating material of gasesin the discharge passage causing back pressure or otherwise varying theeffect of the gas-blast on the arc.

The present invention has for its object to provide resistance switchingin a circuit-breaker of the above-mentioned kind without iving rise tosuch difiiculties.

In the circuit-breaker according to this invention, the arcing contactsare so arranged that the are between them extends generally centrallythrough the nozzle or vent so that the gas-blast flows along and allaround the arc, and the auxiliary electrode, which is connected througha resistance t the first arcing contact and is so arranged that anyrestriking of the are after the arc has gone out will take place to theauxiliary electrode rather than to such first arcing contact, issupported wholly from the high pressure side of the nozzle or vent.

Preferably, the first arcing contact, to which the auxiliary electrodeis connected through a resistance is located on the high pressure sideof the nozzle or vent, and the are (if any) after restriking alsoextends generally centrally in the gas stream flowing through the nozzleor vent. To this end the auxiliary electrode preferably ough aresistance to one of arc energy will be 1i i.-

lies substantially in alignment with the axis of the nozzle or vent, andin a preferred arrangement the first arcing contact is constituted bythe end of a tube surrounding a rod, on the end of which the auxiliaryelectrode is supported. Such rod and tube conveniently have their axessubstantially parallel to the axis of ti" vent. The rod supporting theaux .y

be made of a material having relatively high specific resis ance, sothat the constitutes the resis lnce connect the auxiliary electrode tothe first arcing contact.

The r bei g initially formed by the separating movement o he relativelymovable arc-initiating contacts and being Tolown by the gas blast to aposition in which it extends between the contacts. separating movementof the arc-initiating contacts may take place in a direction transverseto the arc gap between the arcing contacts or in a directionsubstantially parallel thereto. i'he first and second arcing contactsmay be fixed respectively in the high pressure zone and in the lowpressure zone with respect to the gas flow through the nozzle or vent.

Instead however of employing a single nozzle, there may be two nozzles,in axial alignment, the gas-blast being constituted by two streams ofgas flowing towards one another respectively through the two nozzles anddischarging outwardly between the nozzles. In such case there arepreferably two sets of arc-initiating contacts connected in series withone another and respectively associated with the two nozzles, and twofixed arcing contacts disposed respectively on the high pressure sidesof the two nozzles. The two gas streams may cause the two arcs to betransferred from the arc-initiating contacts in such a manher that theymerge into a single arc extending between the two arcing contacts. Withsuch arrangements there may be a'single auxiliary elecconstructions ofcircuit-breaker according thereto are illustrated by way of example inthe accompanying drawings, in which:

Figure 1 is a longitudinal section through one construction,

Figures 2 and 3 are partial views illustrating modifications of theconstruction of Figure 1,

Figures 4 and 5 respectively show two further alternative constructions,and

Figure 6 shows another modification of the construction of Figure 1.

In the construction of Figure 1 which also incorporates the inventionforming the subject of the concurrent U. 8. Patent application SerialNo. 460,161 the circuit-breaker is enclosed within an insulating casingA of generally cylindrical form, to one end of which gas under pressureis introduced, when required, from a suitable reservoir, whilst theother end serves for the discharge of the arc gases.

Although it may be mounted in other positions, the casing A is shownvertical in the drawings with its discharge end uppermost.

At a suitable position in the length of the casing A a metal nozzle Bdiverging towards the discharge end is mounted in a metal housing Bsecured in the casing, and the inner surface B of such housing aroundthe nozzle is formed as a cylinder in which can slide a piston C Ycarrying a bridging contact member C in the form of a group of inwardlyspring-pressed contacts. This piston C is moved by the gas pressure in adirection towards the discharge end of the casing against the action ofa spring C, and the nozzle B is provided with an external contactsurface B with which the bridging contact member C always remains inengagement throughout the piston stroke.

In the normal closed position of the circuitbreaker the bridging contactmember C serves to bridge the gap between the nozzle B and a fixedconducting tube D mounted on the high pressure side of the nozzle inaxial alignment therewith. The end D of this tube D nearest the nozzleconstitutes one of the arcing contacts of the circuit-breaker, and theother arcing contact is constituted either by the low pressure end ofthe nozzle B itself or (as shown) by a central additional contact Bconnected to the nozzle at the low pressure end thereof. The two arcingcontacts D B are thus both fixed, at an appropriate distance apart, andthe gap between them is normally closed by the bridging contact memberC.

Centrally disposed within the conducting tube D is a conducting rod Ewhose end B, constituting an auxiliary electrode, projects from the endof the tube towards or into the nozzle P The other end of this rod E.which is suitably-shrouded with insulating material 3'. projects fromthe other end of the conducting tube D and is supported by webs E.within the main insulating casing A. The'conducting tub'e D itself islikewise suppo ted by webs D within the two sets of webs D 1!. areconnected together through a resistance I", which may conveniently behoused inan annular compartment F surrounding the projecting end of thecentral rod E.

One of the outgoing terminals B of the circuit--breai-zer is connectedto the metal housing 3 around the nozzle 13 and thence to the nozzleitself, whilst the other D is connected to the conducting tube D aroundthe central rod E.

Thus normally when the circuit-breaker is the casing A and 08 closed,the current flows through the nozzle B, the bridging contact member Cand the conducting tube D, whilst the auxiliary electrode E and itsresistance F are out of circuit. When it is desired to open the circuitbreaker, gas under pressure is admitted to the casing A and fills thespaces within and around the conducting tube D. The gas pressure acts onthe piston C and drives it towards the discharge end of the casingwithin the metal housing B thus breaking the connection between thebridging contact member B and the conducting tube D and drawing out anare between these parts. The gas-blast acts on this arc immediately itis formed and tends to blow the arc through the nozzle B. One arc rootremains anchored on the arcing contact constituted by the end D of theconducting tube. The other arc root is blown across from the bridgingcontact member 0 on to the high pressure end of the nozzle B, andsurface to the second arcing contact B at the low pressure end of thenozzle.

In this position the arc will be to some extent bowed out through thenozzle and its main length will lie more or less along the axis of thenozzle in a position favourable to are extinction by the as blast, thegas flowing through the nozzle along the are on all sides thereof. Ifthe auxiliary electrode E projects well into or through the nozzlethroat (as shown) the arc will probably come into contact with thiselectrode, in which case part of the arc will be shunted by theresistance, which will act in some degree to control the are energy.After the arc has gone out, any restriking which may occur will takeplace between the auxiliary electrode E and the second arcing contact 13owing to the fact that the dielectric strength of this gap will be lessthan 46 that of the gap between the auxiliary electrode E and theconducting tube D, and the current will therefore be limited by theresistance F and in the case of an A. C. circuit-breaker will be atunity power factor thus greatly facilitating complete extinction by thegas-blast, which again will flow through the nozzle along the arc on allsides thereof.

In some instances it may be desired to vary the effective breakdowndistances from the nozzle to the auxiliary electrode and to theconducting tube, without alteration of the dimensions of the parts. Thismay be effected, as shown in Figure 6, by providing an insulating lining3' over part of the nozzle B near the throat thereof. This would notmaterially affect the movement of the arc along the nozzle surface,since the gas-blast would readily cause the arc root to jump across theinsulated portion of the nozzle surface.

Again in cases where a separate second arcing contact (such as the bossB shown in Figure l or the bar B shown in Figure 4) is provided thewhole nozzle B may be made of insulating material, as is indicated forexample in Figure 4.

Although it will usually be preferable, it is not essential to theinvention for the vent B controling the flowof gas between the twoarcing contacts to be shaped like a nozzle, and various alternativeshapes may be used. Figure 2 shows a variant in which the gas flow iscontrolled by a ring E carried by and surrounding the auxiliaryelectrode E, within a simple tube B connected to the metal housing BAgain, such a ring E. may be provided in addition to the nozzle B, sothat it lies between the lower end of the nozzle and the end D of theconducting tube D, in such a thence along the nozzle position as to becontacted by the bridging member C during the opening movement, as shownin Figure 3. Such arrangements will bring the resistance F definitelyinto circuit during the opening movement, across part of the arc, andwill thus tend to control the are energy to some extent before the arcgoes out, but in other respects these variants will operate generally inthe manner above described, the gas stream acting to scavenge theapparently small gap between the ring E and the nozzle tube B in Figure2 or the corresponding small gap in Figure 3 and thereby to ensure thatany restriking of the arc will take place in the desired positionbetween the auxiliary electrode E and the second arcing contact B whereit will be readily extinguished.

The direction of movement of the bridging contact member C need not betowards the discharge end of the casing, and in fact such movement neednot take place axially, a lateral arc-initiating movement being shownfor example in Figure 5. The bridging contact member may also bedispensed with altogether, the are being formed by relative axialmovement between the nozzle 12- and the conducting tube D. Such anarrangement, wherein the tube D is movable is shown in Figure 4, whichas already mentioned also serves to show the use of an insulating nozzlewith a bar-shaped second arcing contact B across its low pressure end.

In the construction of Figure 4, the tube 1) is normally connected tothe second arcing contact 13 and to the circuit-breaker terminal Bthrough a stationary group of spring-pressed contact members B and atits lower end carries a piston D which is moved downwardly by the gaspres sure to open the circuit-breaker, the tube D being permanentlyconnected to the circuit-breaker terminal D through a spring contact Dpast which the tube slides.

The auxiliary electrode E is provided, as before, on the end of a rodcentrally mounted within the tube, and is connected to the tube Dthrough a resistance. Figure 4 also serves to show an alternative formof resistance, which may be employed in any of the arrangements insubstitution for a helically wound resistance housed in a compartment,such as F in Figure 1, adjacent to the casing A. In the alternativeshown in Figure 4, the rod E which carries the auxiliary electrode isitself made of a suitable resistance material, such for example assilicon graphite, the auxiliary electrode being in the form of 'a metaltip on the end of the rod. This modification has the advantage ofproviding a compact structure of shorter overall length.

The foregoing arrangements are all shown as single-break arrangements,employing a s ngle nozzle or vent and a single set of arc-initiatincontacts. Such arrangements can readily be modified as double-breakarrangements, by duplieating the parts shown preferably in axialalignment with one another with the two gas streams flowing towards oneanother through the two nozzles and discharging outwardly from the lowpressure space between the nozzles. In such case, of course, theterminal B in each half can be omitted the two metal housings B beingdirectly connected together within the main casing A,

two blasts from both ends.

the auxiliary electrode and its resistance in both halves.

Figure 5 illustrates, quite diagrammatically, one typical example ofsuch alternatives, this figure also showing by way of variant a lateralarcinitiating movement. Thus the lower break in Figure 5 has a nozzle orvent B (shown as of insulating material), as arcing contact Dconstituted by the end of a conducting tube D, and an auxiliaryelectrode E supported on a resistance rod E the tube D and the lower endof the resistance rod E being connected to a terminal rod E whichsupports the resistance rod and passes through a bushing in the wall ofthe main casing. Arc-initiation is effected by means of a contact memberG, for example of the spring finger type, normally engaging with theconducting tube D, but movable laterally out of engagement therewith bymeans of a piston G sliding in a cylindrical housing G exposed to thepressure of the gas in the main casing around the contacts against aspring G The housing G is connected to a similar housing 6- in the upperhalf by a lead G The upper half is of simpler construction and comprisesan insulating nozzle or vent B and a lateral arc-initiating contactmember G similar to those of the lower half, whilst the conducting tubeD is replaced by a simple terminal rod H passing directly through abushing in the main casing wall, the lower end H of such rodconstituting the arcing contact. The auxiliary electrode andtheresistance are omitted altogether in the upper half.

Thus normally the current passes from the terminal rod E through thetube D, the lower contact member G the connector G and the upper contactmember G to the terminal rod H. When the circuit-breaker is to beopened, pressure gas is admitted simultaneousl to the two halves andoperates both arc-initiating contact members G thus drawing out two arcsin series which are'at once blown through the nozzles 13 until theymerge into a single are between the two arcing contacts D and H where itis acted on by the After the arc has gone out, and any restriking willtake place across the gap between the upper arcing contact H and theauxiliary electrode E with the resistance of the rod E in series, suchare readily and easily being extinguished by the gas blasts.

It will be appreciated that the foregoing arrangements have beendescribed by way of example only and that the invention is equallyapplicable to many. other constructional forms of gasblastcircuit-breaker.

What we claim as our invention and desire to secure by Letters Patentis:

1. An electric circuit-breaker comprising in combination a restrictedvent through which a blast of deionising gas flows to assist inextinguishing the arc, arcing contacts so arranged that the are betweenthem extends generally centrally through the vent and the gas-blastflows along and all round the are one of such contacts being located onthe high pressure side and the other on the low pressure side of thevent, an auxiliary electrode, a resistancethrough which such electrodeis connected to the said arcing contact on the high pressure side, meansinsulating said electrode from the arcing contact on the low pressureside and means for supporting the auxiliary electrode wholly from thehigh pressure side of the vent, the auxiliary electrode being soarranged that any restriking of the arc will take place in auxiliaryelectrode is in the form of a rod made of a material having relativelyhigh specific resistance and itself constituting the resistance betweenthe auxiliary electrode and the arcing contact on the high pressur sideof the vent, whilst the said arcing contact on the high pressure side ofthe nozzle is constituted by the end of a tube surrounding such rod, thetube and the rod being disposed substantially in alignment with the axisof the nozzle.

4. An electric circuit-breaker, comprising in combination a restrictedvent through which a blast of deionising gas flows to assist inextinguishing the are, arcing contacts so arranged that the are betweenthem extends generally centrally through the vent and the gas-blastflows along and all round the are, one of such arcing contacts beinglocated on the high pressure side and the other on the low pressure sideof the vent, an auxiliary electrode, a rod located on the high pressureside of the vent and made of material having relatively high specificresistance, such rod acting at one end to support the auxiliaryelectrode and being connected at the other end to the said arcingcontact on the high pressure side so as to constitute a resistanceconnecting the auxiliary electrode to the said arcing contact, and meansinsulating said electrode from the arcing contact on the low pressureside the auxiliary electrode being so arranged that any restriking ofthe arc will take place in series with such resistance to the auxiliaryelectrode rather than to the said arcing contact on the high pressureside..

5. An electric circuit-breaker comprising in combination a nozzlethrough which a blast of deionising gas flows to assist in extinguishingthe arc, arcing contacts so arranged that the arc between them extendsgenerally centrally through the nozzle and the gas-blast flows along andall round the arc, one of such arcing contacts being constituted by theend of a tube located on the high pressure side of the nozzle, the otherof said contacts being located on the low pressure side of the nozzle,an auxiliary electrode mounted substantially in alignment with thenozzle axis, a rod disposed within the arcing contact tube on the highpressure side of the nozzle and constituting the support for theauxiliary electrode, a resistance through which the auxiliary electrodeis connected to the arcing contact tube, and means insulating saidelectrode from the arcing contact on th low pressure side of the nozzle,the auxiliary electrode being so arranged that any restriking of the arcwill take place in series with the resistance to such electrode ratherthan to the arcing contact tube.

6. The combination'with the features set forth located on the highpressure side and the other in claim 5, of relatively movablearc-initiating contacts disposed on the high pressure side of thenozzle, the are being initially formed by the separation of suchcontacts and being immediately transferred therefrom by the gas-blast tothe arcing contacts which are fixed. 7. An electric circuit-breaker,comprising in on the low pressure side of the vent, an auxiliaryelectrode, a rod located on the high pressure side of the vent and madeof material having relatively high specific resistance, such rod actingat one end to support the auxiliary electrode and being connected at theother end to the said arcing contact on the high pressure side so as toconstitute a resistance connecting the auxiliary electrode to the saidarcing contact, and means insulating said electrod from the arcingcontact on the low pressure side the auxiliary electrode being soarranged that any restriking of the arc will take place in series withsuch resistance to the auxiliary electrode rather than to the saidarcing contact on the high pressure side.

8. An electric circuit-breaker as claimed in claim 7, in which themoving arc-initiating contact is in the form of a tube, and the arcingcontact on the high pressure side is constituted by the end of suchtube, the tube surrounding the resistance rod and constituting theconnection therefrom to the said arcing contact.

9. An electric circuit-breaker comprising in combination a restrictedvent through which a blast of deionising gas fiows to assist inextinguishing the arc, relatively movable arc-initiating contacts whichare disposed on the high pressure side of the restricted vent and bywhose separation the arc is initially formed, fixed arcing contacts towhich the arc is transferred from the arc-initiating contacts by thegas-blast the arc when so transferred extending generally centrallythrough the vent so that the gas-blast flows along and all round the areone of such contacts being located on the high pressure side and theother on the low pressure side of the vent, an auxiliary electrode, aresistance through which such electrode is connected to the said fixedarcing contact on th high pressure side, means insulating said electrodefrom the arcing contact on the low pressure side and means forsupporting the auxiliary electrode wholly from the high pressure side ofthe vent, the auxiliary electrode being so arranged that any restrikingof the arc will take place in series with the resistance to suchelectrode rather than to the said fixed arcing contact on th highpressure side.

10. An electric circuit-breaker as claimed in claim 9, in which theauxiliary electrode lies substantially in alignment with the axis of therestricted vent, so that any restriking of the arc will take placegenerally centrally with respect to the gas stream flowing through thevent.

11. An electric circuit-breaker, comprising in combination a restrictedvent through which a blast of deionising gas flows to assist inextinguishing the arc, relatively movable arc-initiating contacts whichare disposed on the high pressure side of the restricted vent and bywhose separathe vent so that the gas-blast flows along and all round thearc, one of such arcing contacts being located on the high pressure sideand the other on the low pressure side of the vent, an auxiliaryelectrode, a resistance through which such electrode is connected to thesaid arcing contact on the high pressure side, means insulating saidelectrode from the other of said arcing contacts, and means forsupporting the auxiliary electrode wholly from the high pressure side ofthe vent, the auxiliary electrode being so arranged that any restrikingof the arc will take place in series with such resistance to theauxiliary electrode rather than to the said arcing contact on the highpressure side, the separating movement of the arcinitiating contactstaking place in a direction transverse to the arc gap between the arcingcon tacts.

12. An electric circuit-breaker, comprising in combination a restrictedvent through which a blast of deionising gas flows to assist inextinguishing the are, relatively movable arc-initiating contacts whichare disposed on the high pressure side of the restricted vent and bywhose separation the arc is initially formed, arcing contacts to whichthe arc is transferred from the arcinitiating contacts by the gas-blast,the are when so transferred extending generally centrally through thevent so that the gas-blast flows along and all round the arc, one ofsuch arcing con-- tacts being located on the high pressure side and theother on the low pressure side of the vent, an auxiliary electrode, aresistance through which such electrode is connected to the said arcingcontact on the high pressure side, means insulating said electrode fromthe other of said arcing contacts, and means for supporting theauxiliary electrode wholly from the high pressure side of the vent, theauxiliary electrode being so arranged that any restriking of the arcwill take place in series with such resistance to the auxiliaryelectrode rather than to the said arcing contact on the high pressureside, the separating movement of the arc-initiating contacts takingplace in a direction substantially parallel to the are gap between thearcing contacts.

13. An electric circuit-breaker comprising in combination two nozzles inaxial alignment sides of -the two nozzles, two sets of arc-initiatingcontacts located respectively on the high pressure sides of the twonozzles, means for separating such arc-initiating contacts and therebydrawing out two arcs in series, such arcs being transferred from thearc-initiating contacts by the gas-blast so that they merge into asingle arc extending between the two fixedarcing contacts through thetwo nozzles, at least one auxiliary electrode. a resistance throughwhich such electrode is connected to one of the arcing contacts, andmeans insulating said electrode from the other of said arcing contacts,the arrangement being such that any restriking of the arc will takeplace to the auxiiiary electrode rather than to the arcing con-- '5' ctto which it is connected through the re- 71188, and. means forsupporting the auxiliary trode wholly from the high pressure side of oneof the nozzles. 7

15. An electric circuit-breaker, comprising in combination two nozzlesin axial alignment through which a blast of deionising gas flowsrespectively in two streams directed towards-one another and dischargingoutwardly from the space between the'two nozzles, two sets ofarcinitiating contacts located respectively on the high pressure sidesof the two nozzles, means forseparating such arc-initiating contacts andthereby drawing out two arcs in series, arcing contacts to which thearcs are transferred by the gas-blast from the arc-initiating contactsso that they ex- .tend through the nozzles, at least one auxiliarythrough which a blast of deionising gas flows re- 5 spectively in twostreams directed towards one another and discharging outwardly from thespace between the nozzles, two sets of arc-initiating contacts locatedrespectively on the high pressure sides of the two nozzles, means forseparating such arc-initiating contacts and thereby drawing out two arcsinseries, arcing contacts to which the arcs are transferred by the gasblast from the arc-initiating contacts so that they extend through thenozzles, at least one auxiliary electrode', a resistance through whichsuch auxiliary electrode is connected to one of the arcing contacts thearrangement being such that any restriking of the arc will take place tothe auxiliary electrode rather than to such arcing contact, and meansfor supporting the auxiliary electrode wholly from the high pressureside of one of the nozzles.

14. An electric circuit-breaker, comprising in combination two nozzles.in axial alignment through which a blast of deionising gas flowsrespectively in two streams directed towards one another and dischargingoutwardly from the space between the two nozzles, two fixed arcingcontacts located respectively on the high pressure electrode, a rodmounted on the high pressure side of one of the nozzles and made ofmaterial having relatively high specific resistance, such rod acting atone end to support the auxiliary electrode and being connected at itsother end to one of the arcing contacts so as to constitute a resistancebetween the auxiliary electrode and.

the said arcing contact, and means insulating said electrode from thearcing contact on the low pressure side, the auxiliary electrode beingso arranged that any restriking of the-arc will take place in serieswith the resistance to the auxiliary electrode rather than to the arcingcontact to which it is connected.

16. An electric circuit-breaker, comprising in combination two nozzlesin axial alignment through which a blast of deionising gas flowsrespectively in two streams directed towards one another and dischargingoutwardly from the space between the two nozzles, two sets, of'arcinitiating contacts located. respectively on the high pressure sidesof the two nozzles, means for separating such arc-initiating contactsand thereby drawing out two arcs in series, arcing contacts to which thearcs are transferred by the gas-blast from the arc-initiating contactsso that they extend through the nozzles, at least one auxiliaryelectrode, a resistance through which such electrode is connected to oneof the arcing contacts the arrangement being such that any restriking ofthe arc will take place to the auxiliary electrode rather than to thearcing contact to which it is connected through the resistance, meansinsulating said electrode from the arcing contact on the low pressureside, and means for supporting the auxiliary electrode wholly from thehigh pressure side of one of the nozzles, the separating movement of thearc-initiating contacts taking place in a direction transverse to thearc gap between the arcing contacts.

- DONALD FOSTER AMER.

ARTHUR RAWLING.

